Yeah seasons 3 through 8 were the Conan O'Brien years. That's the golden era.

But there are excellent episodes outside of that. I personally think "SE12 EP18 - Trilogy of Errors" is a top 5 episode. It's the one where marge cuts off homer's thumb, Milhouse finds fireworks in a cave and Lisa builds a party grammar robot. I haven't seen enough of seasons beyond like 20 or so to comment on them, but Ive heard they've actually been hitting a solid stride since the pandemic.